Ultrathin Carbon Films Prepared by Negative Cluster-Beam Technology

We develop a miniaturized chamber installed on a tandetron accelerator into which negative ions of small carbon clusters are transported. Negative clusters C₁⁻− C₁₀⁻ are obtained with beam currents of 1–10⁴ nA at energies of 10–20 keV. C₂⁻ beams of 0.2 µA are used to directly deposit carbon films on SiO₂/Si substrates. Formation of ultrathin carbon films are demonstrated by Raman scattering, which reveals the evolution of the graphitic peak (1550 cm⁻²) with deposition time.